Traditional power electronic applications usually involve delivering power from one or more specific sources in a controlled fashion to a specific load. Often these power sources are either alternating current (AC) or direct current (DC) sources, and the loads are alternating current (AC) or direct current (DC) loads. Existing power conversion equipment utilizes one or more sets of specific fixed function hardware to provide the desired power from a source to a load. For example, the fixed function hardware generally includes a rectifier for AC to DC power conversion, a converter for DC to DC power conversion, or an inverter for DC to AC power conversion.
Some distributed power generation applications involve power conversion between devices that can act either as sources of electrical power or loads for electrical power. Examples of such bi-directional sources/loads include battery systems and regenerative-mode motors. Distributed power generation often involves treating multiple sources, or loads, of electrical power that are AC, DC, or can switch from one to the other. Examples of such sources or loads include micro-grid systems that tie the AC power grid with DC photovoltaic (PV) panels.
Utilizing existing power electronics and control systems for multi-source or multi-load, bidirectional, AC/DC power flow applications can result in systems that lack flexibility. Such systems are often implemented with several separate conversion stages, resulting in reduced power efficiency and higher system cost.